To the best of my knowledge, no third-party PDF plugin on the Mac allows for the inline viewing of PDFs in Google Chrome, fortunately there is a way. As of Chrome 6, Google bundles an experimental PDF plugin, which is disabled by default.

To enable it:

Type about:plugins in the omnibox.

You should see a disabled plugin called 'Chrome PDF Viewer;' click the Enable button under this plugin.

You should now be able to view PDFs in Chrome. There are a few rough edges to this plugin. The occasional PDF will not display properly (in particular, it seems to choke on PDFs that have restrictions in effect — printing, copying, etc), but the vast majority show up just fine. The viewer is very fast, and has resizing controls available in the bottom-right corner of the window.

Note that there is currently no loading indicator for PDFs, so if you click on a large document, it may seem like the tab has frozen, but it is in fact just the PDF loading silently.

[crarko adds: I tested this, and it works as described. It was fine with the couple of PDFs I tried.]

I use the Docs PDF Chrome Viewer extension, which does essentially the same thing, except that you can also choose to save documents into Google Docs and directly download linked PDFs from a popup menu.

Some of the restrictions stuff you mentioned apply for this as well. Sites like scientific journals that have strict login requirements sometimes don't display properly but can be directly downloaded just fine.

FYI, for anyone who isn't clear on the difference, what the Google Docs viewer does is to redirect any PDF you try to access to the google docs site, where it is loaded in the google docs web-based PDF viewer.

Now, this is what I used to use, but I found that it seems to have trouble with a lot of websites, and would usually fail entirely on larger PDFs — not to mention generally being a lot slower to load then the built-in PDF viewer. Your mileage may vary, of course.

After seeing all the plug ins, I noticed that Flip-4-Mac was turned off also, which enables you to use QuikTime to view Windows Media Files in your Web browser. Should I enable this too? What does Chrome use in Mac to watch Windows Media Files if this is turned off?

I would leave it disabled. WMV videos seem to play fine in Chrome even with it turned off (although it took me like 10 minutes to locate one online. Even Microsoft has thoroughly abandoned the format in favor of Silverlight), and Google may be auto-disabling it for a reason.

Unfortunately, this hint does not work so well on Chrome 7. Chrome 7 includes a newer version of the PDF plugin. It has what appears to be an early implementation of a page thumbnail view on the right side of the window, unfortunately, it is also virtually unusable. Scrolling doesn't work properly, and the page thumbnails appear on top of the PDF content. Obviously very much a work in progress.